Light emitting device, light emitting diode package, backlight unit, and liquid crystal display

ABSTRACT

A display apparatus including a display panel, and a backlight to provide light toward the display panel, the backlight including a circuit board, an optical layer disposed on the circuit board, at least one light emitter disposed between the circuit board and the optical layer and including a light emitting structure disposed on the circuit board and having first and second conductivity type semiconductor layers and an active layer therebetween, first and second electrode pads electrically connected to the first and second conductivity type semiconductor layers, respectively, a reflector on the light emitting structure, a light transmitting layer disposed on the circuit board and contacting the light emitter, and a dam disposed on the circuit board and surrounding the light emitter and including a portion having a curved shape.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.17/110,293, filed on Dec. 3, 2020, which is a Continuation of U.S.patent application Ser. No. 17/095,066, filed on Nov. 11, 2020, which isa Bypass Continuation of International Patent Application No.PCT/KR2019/007103, filed on Jun. 12, 2019, and claims benefits of U.S.Provisional Application No. 62/697,078, filed on Jul. 12, 2018, U.S.Provisional Application No. 62/697,552, filed on Jul. 13, 2018, and U.S.Provisional Application No. 62/702,445, filed on Jul. 24, 2018, each ofwhich is hereby incorporated by reference for all purposes as if fullyset forth herein.

BACKGROUND Field

Exemplary embodiments relate to a light emitting device, a lightemitting diode package, a backlight unit, and a liquid crystal display.

Discussion of the Background

As one type of a flat panel display (FPD), a liquid crystal display(LCD) is widely used due to its display quality and high contrast ratio.

The liquid crystal display includes liquid crystals, which allow lightto pass therethrough or blocking light depending upon an arrangementdirection of liquid crystal molecules. The liquid crystal display hasadvantages of a smaller thickness and lower power consumption than otherdisplays. The liquid crystal display displays an image through a displaypanel including the liquid crystals between two glass substrates. Thedisplay panel is not self-emissive, and thus, requires a backlight unitfor supplying light to the display panel.

Since the liquid crystal display generally blocks light based on thearrangement of the liquid crystal molecules and polarization filterswith a light source of the backlight unit kept in a turned-on state, theliquid crystal display suffers from significant power consumption. Tosolve this problem, the liquid crystal display may adopt local dimming.Local dimming is performed by locally adjusting the intensity of lightor locally blocking light through partial adjustment of brightness of alight source, instead of blocking light based on arrangement of theliquid crystal molecules, which substantially reduces power consumptionupon operation of the liquid crystal display. In addition, local dimmingcan further improve contrast ratio. Such local dimming may be used in adirect-lighting type backlight unit, in which the light source isdisposed below the display panel, but may not be suitable for anedge-lighting type backlight unit, in which the light source is disposedon a side surface of a light guide plate.

The direct-lighting type backlight unit employs multiple light emittingdiodes. The multiple light emitting diodes are arranged in a matrixbelow the display panel, such that light emitted from the light emittingdiodes enters the display panel through an optical sheet. In this case,since the light emitting diodes are spot light sources, it is necessaryto ensure uniform distribution of light emitted from the light emittingdiodes. As such, there is a need for very dense arrangement of the lightemitting diodes or for positioning the light emitting diodes to bespaced apart from display panel. Further, a diffusion lens may be usedto achieve uniform spreading of light emitted from the light emittingdiodes in a lateral direction. As such, it is generally difficult toreduce the thickness of the direct-lighting type backlight unit due toincrease in distance between a light source and an optical sheet evenwithout using the light guide plate.

Moreover, while the usage of a diffusion lens may reduce the number oflight emitting diodes used in the backlight unit by increasing a regioncovered by one light emitting diode, such may be disadvantageous whenemploying local dimming as the region covered by one light emittingdiode would be increased.

Moreover, in the direct-lighting type backlight unit, since lightemitted from a light emitting diode chip affects a region incident withlight emitted from adjacent light emitting diode chip, it is difficultto achieve a clear blackout effect in such region due to light emittedfrom the adjacent light emitting diode chip even when the light emittingdiode chip is turned off.

Moreover, an optical device emits a greater amount of light through anupper surface thereof than through a side surface thereof. Since thereis a significant difference in brightness between an upper region of thelight emitting device and a peripheral region thereof, bright spots aremainly generated in the upper region of the light emitting device amongthe entire light emitting region of the backlight unit. Accordingly, thebacklight unit adopting typical light emitting devices has a problem oflow uniformity of light emitted therefrom.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Light emitting devices constructed according to exemplary embodiments ofthe invention are capable of suppressing a spot phenomenon whileimproving luminous uniformity.

Exemplary embodiments also provide a light emitting diode package and abacklight unit having improved contrast ratio depending upon on/offoperation of an individual light emitting diode chip.

Exemplary embodiments still provide a backlight unit having more uniformdistribution of light without using a diffusion lens and being suitablefor local dimming.

Exemplary embodiments yet provide a direct-lighting type backlight unithaving a thin thickness.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

A light emitting device according to an exemplary embodiment includes alight emitting diode chip, a light reflection member disposed on anupper surface of the light emitting diode chip, a light transmittingresin covering at least a side surface of the light emitting diode chip,and a light blocking member covering an upper surface of the lighttransmitting resin.

A light emitting diode package according to another exemplary embodimentincludes a circuit board, a light emitting diode chip mounted on thecircuit board, a reflection member formed on an upper surface of thelight emitting diode chip, and a dam disposed on the circuit board tosurround a lateral side of the light emitting diode chip, in which aside surface of the light emitting diode chip is spaced apart from thedam.

A backlight unit according to still another exemplary embodiment a lightemitting diode package including a circuit board, a light emitting diodechip mounted on the circuit board, a reflection member formed on anupper surface of the light emitting diode chip, and a dam formed on thecircuit board, and an optical member disposed on the light emittingdiode package. The dam is disposed to surround a lateral side of thelight emitting diode chip and is spaced apart from a side surface of thelight emitting diode chip.

A backlight unit according to yet another exemplary embodiment includesa circuit board, a plurality of light emitting devices arranged on thecircuit board, and a combined optical sheet disposed on the lightemitting devices, in which each of the light emitting devices includes adistributed Bragg reflector on an upper surface thereof and is mountedon the circuit board to be independently driven.

A liquid crystal display according to another exemplary includes abacklight unit, and a display panel disposed on the backlight unit, thebacklight unit including a circuit board, a plurality of light emittingdevices arranged on the circuit board, and a combined optical sheetdisposed on the light emitting devices, in which each of the lightemitting devices includes a distributed Bragg reflector on an uppersurface thereof and is mounted on the circuit board to be independentlydriven.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention, and together with the description serve to explain theinventive concepts.

FIG. 1 is a schematic view of a light emitting device according to afirst exemplary embodiment.

FIG. 2 is a schematic view of a light emitting diode chip and areflection member according to an exemplary embodiment.

FIG. 3 is a schematic view of a light emitting device according to asecond exemplary embodiment.

FIG. 4 is a graph depicting brightness of a light emitting deviceaccording to an exemplary embodiment and a conventional light emittingdevice.

FIG. 5 is a graph depicting brightness of a light emitting deviceaccording to exemplary embodiments with a varying thickness of awavelength conversion member.

FIG. 6 and FIG. 7 are schematic views of light emitting devicesaccording to third and fourth exemplary embodiments.

FIG. 8 is a schematic view of a light emitting device according to afifth exemplary embodiment.

FIG. 9 , FIG. 10 , and FIG. 11 are schematic views illustrating a methodof manufacturing the light emitting device according to the fifthexemplary embodiment.

FIG. 12 and FIG. 13 are schematic views of a light emitting diodepackage according to a first exemplary embodiment.

FIG. 14 is a graph depicting beam angle depending upon angle (0) from alight emitting surface to an inner wall of a dam.

FIG. 15 is a graph comparing beam angle of the light emitting diodepackage according to the first exemplary embodiment with beam angle of aconventional light emitting diode package.

FIG. 16 is a schematic view of a light emitting diode package accordingto a second exemplary embodiment.

FIG. 17 , FIG. 18 , and FIG. 19 are schematic views of light emittingdiode packages according to third to fifth exemplary embodiments.

FIG. 20 , FIG. 21 , FIG. 22 , and FIG. 23 are schematic views of lightemitting diode packages according to sixth to ninth exemplaryembodiments.

FIG. 24 is a schematic cross-sectional view of the light emitting diodepackage of FIG. 20 .

FIG. 25 is a graph comparing beam angle of the light emitting diodepackage according to the sixth exemplary embodiment with beam angle of aconventional light emitting diode package.

FIG. 26 is a schematic view of a backlight unit according to a firstexemplary embodiment.

FIG. 27 and FIG. 28 are schematic views of backlight units according tosecond and third exemplary embodiments.

FIG. 29 is a schematic partially exploded sectional view of a liquidcrystal display according to an exemplary embodiment.

FIG. 30 is a schematic plan view of a circuit board on which lightemitting devices are arranged according to an exemplary embodiment.

FIG. 31 is a schematic partially exploded sectional view of a backlightunit of a liquid crystal display according to another exemplaryembodiment.

FIG. 32 is a schematic enlarged cross-sectional view of a light emittingdevice applied to the backlight unit shown in FIG. 31 .

FIG. 33 is a schematic cross-sectional view of a light emitting deviceaccording to another exemplary embodiment applied to a backlight unit.

FIG. 34 , FIG. 35 , FIG. 36 , FIG. 37 , FIG. 38 , and FIG. 39 areschematic cross-sectional views of a combined optical sheet according toexemplary embodiments.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various exemplary embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form in order to avoid unnecessarilyobscuring various exemplary embodiments. Further, various exemplaryembodiments may be different, but do not have to be exclusive. Forexample, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the D1-axis, the D2-axis,and the D3-axis are not limited to three axes of a rectangularcoordinate system, such as the x, y, and z-axes, and may be interpretedin a broader sense. For example, the D1-axis, the D2-axis, and theD3-axis may be perpendicular to one another, or may represent differentdirections that are not perpendicular to one another. For the purposesof this disclosure, “at least one of X, Y, and Z” and “at least oneselected from the group consisting of X, Y, and Z” may be construed as Xonly, Y only, Z only, or any combination of two or more of X, Y, and Z,such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should notnecessarily be construed as limited to the particular illustrated shapesof regions, but are to include deviations in shapes that result from,for instance, manufacturing. In this manner, regions illustrated in thedrawings may be schematic in nature and the shapes of these regions maynot reflect actual shapes of regions of a device and, as such, are notnecessarily intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

According to an exemplary embodiment, a light emitting device mayinclude: a light emitting diode chip; a light reflection member disposedon an upper surface of the light emitting diode chip; a lighttransmitting resin covering at least a side surface of the lightemitting diode chip; and a light blocking member covering an uppersurface of the light transmitting resin.

The light transmitting resin may cover the side surface of the lightemitting diode chip while exposing a side surface of the lightreflection member.

The light blocking member may cover the upper surface of the lighttransmitting resin and the side surface of the light reflection member.

In another exemplary embodiment, the light transmitting resin may coverthe side surface of the light emitting diode chip and a side surface ofthe light reflection member.

The light blocking member may cover the upper surface of the lighttransmitting resin and an upper surface of the light reflection member.

Alternatively, the light blocking member may cover the upper surface ofthe light transmitting resin while exposing at least a portion of anupper surface of the light reflection member.

According to another exemplary embodiment, the light transmitting resinmay cover the side surface of the light emitting diode chip and an uppersurface of the light reflection member.

The upper surface of the light transmitting resin may have a steppedstructure in which a peripheral region of the upper surface thereof hasa thickness less than that in a central region of the upper surfacethereof.

The light reflection member may include a metal reflector or adistributed Bragg reflector (DBR).

The light blocking member may be a white resin reflecting light.

The light emitting device may further include a wavelength conversionmaterial dispersed in the light transmitting resin to convert awavelength of light emitted from the light emitting diode chip.

According to an exemplary embodiment, a light emitting diode package mayinclude: a circuit board; a light emitting diode chip mounted on thecircuit board; a reflection member formed on an upper surface of thelight emitting diode chip; and a dam disposed on the circuit board andsurrounding a lateral side of the light emitting diode chip. A sidesurface of the light emitting diode chip may be spaced apart from thedam. In addition, an angle from an optical axis of a light emittingsurface of the light emitting diode chip to an upper corner of an innerwall of the dam may be greater than an angle corresponding to a peakbeam angle of the light emitting diode chip.

The light emitting diode package may further include a lighttransmitting resin covering the light emitting diode chip and thereflection member.

The transmitting resin may include a wavelength conversion materialdispersed therein.

The circuit board may be integrally formed with the dam, or the dam maybe separately formed on the circuit board.

The dam may be formed of a material that does not transmit light emittedfrom the light emitting diode chip therethrough or reflect light emittedfrom the light emitting diode chip.

The reflection member may include at least one layer formed of metal, adistributed Bragg reflector (DBR), or a resin including a reflectivematerial.

A backlight unit according to an exemplary embodiment may include: alight emitting diode package and an optical member disposed on the lightemitting diode package. The light emitting diode package may include acircuit board, a light emitting diode chip mounted on the circuit board,a reflection member formed on an upper surface of the light emittingdiode chip, and a dam formed on the circuit board. The dam may bedisposed to surround a lateral side of the light emitting diode chip andbe spaced apart from a side surface of the light emitting diode chip. Inaddition, an angle from an optical axis of a light emitting surface ofthe light emitting diode chip to an upper corner of an inner wall of thedam may be greater than an angle corresponding to a peak beam angle ofthe light emitting diode chip.

The backlight unit may further include a light transmitting resincovering the light emitting diode chip and the reflection member.

The transmitting resin may include a wavelength conversion materialdispersed therein.

The circuit board may be integrally formed with the dam, or the dam maybe separately formed on the circuit board.

The dam may be formed of a material that does not transmit light emittedfrom the light emitting diode chip therethrough or reflect light emittedfrom the light emitting diode chip.

The reflection member may include at least one layer formed of metal, adistributed Bragg reflector (DBR), or a resin including a reflectivematerial.

The light emitting diode package may be spaced apart from the opticalmember to form a space between the light emitting diode package and theoptical member.

The backlight unit may further include a sealing member formed of alight transmitting material and filling the space between the lightemitting diode package and the optical member.

The sealing member may include a light diffuser dispersed therein.

A backlight unit according to an exemplary embodiment includes: acircuit board; a plurality of light emitting devices arranged on thecircuit board; and a combined optical sheet disposed on the lightemitting devices, in which each of the light emitting devices includes adistributed Bragg reflector on an upper surface thereof and is mountedon the circuit board to be independently driven.

The backlight unit may further include a wavelength conversion sheetconverting a wavelength of light emitted from the light emittingdevices. Furthermore, the wavelength conversion sheet may be integratedinto the combined optical sheet.

Each of the light emitting devices may include a wavelength conversionmember disposed on a side surface thereof.

A portion of the wavelength conversion member may cover the distributedBragg reflector.

Each of the light emitting devices may further include a light blockingmember covering the wavelength conversion member.

The light blocking member may include a white resin.

The wavelength conversion member may have a stepped structure formed atleast one corner thereof and the light blocking member may cover thestepped structure.

The combined optical sheet may include at least two sheets selected fromamong a diffusion sheet, a prism sheet, a polarization film, and a finelens sheet.

The combined optical sheet may include at least one diffusion sheet andat least one prism sheet.

A liquid crystal display according to an exemplary embodiment includes:a backlight unit; and a display panel disposed on the backlight unit,the backlight unit including: a circuit board; a plurality of lightemitting devices arranged on the circuit board; and a combined opticalsheet disposed on the light emitting devices, in which each of the lightemitting devices includes a distributed Bragg reflector on an uppersurface thereof and is mounted on the circuit board to be independentlydriven.

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings.

FIG. 1 is a schematic view of a light emitting device according to afirst exemplary embodiment.

Referring to FIG. 1 , a light emitting device 100 according to the firstexemplary embodiment includes a light emitting diode chip 110, a lightreflection member 120, a wavelength conversion member 130, and a lightblocking member 140.

The light emitting diode chip 110 emits light through upper and sidesurfaces thereof. The light emitting diode chip 110 is a semiconductordevice having a light emitting structure on a growth substrate. Detailsof the light emitting diode chip 110 will be described below.

The light reflection member 120 covers the upper surface of the lightemitting diode chip 110. The light reflection member 120 reflects lightemitted through the upper surface of the light emitting diode chip 110.Light emitted through the upper surface of the light emitting diode chip110 is light generated from an active layer of the light emitting diodechip 110 and passes through the upper surface of the light emittingdiode chip 110.

The light reflection member 120 reflects light passing through the uppersurface of the light emitting diode chip 110, such that light isreflected back to the light emitting diode chip 110 and emitted throughthe side surface of the light emitting diode chip 110. In this manner,in a direct-lighting type backlight unit, light emitted from the lightemitting device 100 can be broadly spread in a lateral direction,thereby increasing a luminous area of the light emitting device 100.

The light reflection member 120 may be formed of any material capable ofreflecting light emitted from the light emitting diode chip 110. Forexample, the light reflection member 120 may be a distributed Braggreflector (DBR). The DBR may include a dielectric layer, such as SiO₂,TiO₂, SiN, and the like, and may be formed by alternately stackinglayers having different indices of refraction. Alternatively, the lightreflection member 120 may include a metal reflector. For example, ametal reflection layer, such as Ag and Al, may be formed on the uppersurface of the light emitting diode chip 110. Still alternatively, thelight reflection member 120 may include both the DBR and the metalreflection layer.

The light reflection member 120 may be formed together with the lightemitting diode chip 110 in a process of manufacturing the light emittingdiode chip 110. More particularly, the light reflection member 120 maybe formed before individually dicing the light emitting diode chips 110.In this case, the light emitting diode chip 110 may include the lightreflection member 120. Hereinafter, the light emitting diode chip 110having an upper surface through which light is emitted and the lightreflection member 120 formed thereon will be separately described.

The wavelength conversion member 130 converts the wavelength of lightemitted from the light emitting diode chip 110. According to theillustrated embodiment, the wavelength conversion member 130 covers theside surface of the light emitting diode chip 110 and a side surface ofthe light reflection member 120.

The wavelength conversion member 130 includes a light transmitting resin131 and a wavelength conversion material 132 dispersed in the lighttransmitting resin 131. For example, the light transmitting resin 131may be formed of a light transmitting material well known in the art,such as an epoxy resin, a silicone resin, and the like, and thewavelength conversion material 132 may include phosphors or quantumdots. The phosphor refers to an inorganic or organic compound thatconverts light absorbed from the light emitting diode chip 110 intolight having a different wavelength depending upon a difference inenergy level of a compound constituting the phosphor. The quantum dotrefers to a semiconductor nanocrystal that converts the absorbed lightinto light having a different wavelength depending upon the magnitude ofa band gap.

The wavelength of light emitted through the light emitting diode chip110 is converted by the wavelength conversion member 130, which coversthe side surfaces of the light emitting diode chip 110 and the lightreflection member 120. Accordingly, light subjected to wavelengthconversion by the wavelength conversion material is emitted through theside surface of the light emitting device 100. Furthermore, somefraction of light emitted from the light emitting diode chip 110 may beemitted through the side surface of the light emitting device 100without wavelength conversion.

According to the illustrated exemplary embodiment, since the lightemitting device 100 emits light subjected to wavelength conversion, aseparate wavelength conversion sheet may be obviated from a displayapparatus. The wavelength conversion member 130 may not only convert thewavelength of light, but also protect the light emitting diode chip 110from external materials, such as moisture, dust, and the like. Inaddition, the wavelength conversion member 130 may protect the lightemitting diode chip 110 from external impact.

Although the light emitting device 100 according to the illustratedexemplary embodiment includes the wavelength conversion member 130 thathas the wavelength conversion material 132 dispersed in the lighttransmitting resin 131, the inventive concepts are not limited thereto.For example, in some exemplary embodiments, the wavelength conversionmaterial 132 may be omitted depending upon a desired color of light.

The light blocking member 140 may cover an upper surface of thewavelength conversion member 130 and an upper surface of the lightreflection member 120. The light blocking member 140 may reflect orabsorb light passing through the upper surface of the wavelengthconversion member 130. For example, the light blocking member 140 mayinclude a metal layer, a DBR, or a white resin. The white resin may beobtained by depositing or coating a white paint onto a resin or bydispersing a reflective material in a resin. Alternatively, the lightblocking member 140 may be obtained by depositing or coating a blackpaint onto a resin or by dispersing a light absorbing material in aresin to block light by absorption.

Accordingly, the light blocking member 140 may cause wavelengthconverted light to be broadly spread in a lateral direction by blockinglight emitted from the light emitting diode chip 110 in an upwarddirection thereof through the wavelength conversion member 130.

The light blocking member 140 may also prevent light emitted from thelight emitting device 100 from being reabsorbed by the light emittingdevice 100. For example, the light blocking member 140 may prevent lightreflected by an optical sheet disposed on the light emitting device 100from being reabsorbed into the light emitting diode chip 110 through theupper surface of the wavelength conversion member 130 and the uppersurface of the light emitting diode chip 110. In particular, the lightblocking member 140 formed of a reflective layer or a white resin mayreflect light that has been reflected back to the light emitting device100 by the optical sheet, thereby improving luminous efficacy.

According to the illustrated exemplary embodiment, the light emittingdevice 100 includes the light reflection member 120 and the lightblocking member 140 disposed on the light emitting diode chip 110. Thelight reflection member 120 and the light blocking member 140 mayefficiently prevent discharge of light or reabsorption of external lightthrough the upper surface of the light emitting diode chip 110. As such,the light emitting device 100 emits light substantially through the sidesurface thereof, thereby ensuring broad distribution of light.

Hereinafter, descriptions of the components forming the light emittingdevice 100 already made above will be given in brief or omitted.

FIG. 2 is a schematic view of a light emitting diode chip and areflection member according to an exemplary embodiment.

The light emitting diode chip 110 and the light reflection member 120according to the illustrated exemplary embodiment are substantially thesame as the light emitting diode chip and the light reflection member ofthe light emitting device described above with reference to FIG. 1 .

The light emitting diode chip 110 according to the illustrated exemplaryembodiment has a horizontal structure in which both electrodes areformed at a lower side thereof.

Referring to FIG. 2 , the light emitting diode chip 110 may include asubstrate 11, a light emitting structure 12, a transparent electrodelayer 16, a first electrode pad 17, a second electrode pad 18, and areflective layer 19.

The substrate 11 may be transparent. For example, the substrate 11 maybe a sapphire substrate or a SiC substrate. Alternatively, the substrate11 may be a growth substrate, for example, a patterned sapphiresubstrate (PSS), which is suitable for growth of GaN-based compoundsemiconductor layers thereon.

The light emitting structure 12 is disposed at a lower side of thesubstrate 11. The light emitting structure 12 includes a firstconductivity type semiconductor layer 13, a second conductivity typesemiconductor layer 15, and an active layer 14 interposed between thefirst conductivity type semiconductor layer 13 and the secondconductivity type semiconductor layer 15. The first conductivity typeand the second conductivity type may have opposite conductivities, andthe first conductivity type may be n-type and the second conductivitytype may be p-type, or vice versa.

Each of the first conductivity type semiconductor layer 13, the activelayer 14, and the second conductivity type semiconductor layer 15 may beformed of a GaN-based compound semiconductor material. Each of the firstconductivity type semiconductor layer 13 and the second conductivitytype semiconductor layer 15 may be formed as a single layer, as shown inFIG. 2 . Alternatively, at least one of the first conductivity typesemiconductor layer 13 and the second conductivity type semiconductorlayer 15 may have a multilayer structure. The active layer 14 may have asingle quantum well structure or a multi-quantum well structure. In someexemplary embodiments, a buffer layer may be formed between thesubstrate 11 and the first conductivity type semiconductor layer 13.

The first conductivity type semiconductor layer 13, the secondconductivity type semiconductor layer 15, and the active layer 14 may beformed by metal organic chemical vapor deposition (MOCVD) or molecularbeam epitaxy (MBE). Further, the second conductivity type semiconductorlayer 15 and the active layer 14 may be subjected to patterning throughphotolithography and etching so as to expose some regions of the firstconductivity type semiconductor layer 13. In this case, some portions ofthe first conductivity type semiconductor layer 13 may also be subjectedto patterning.

The transparent electrode layer 16 is disposed on a lower surface of thesecond conductivity type semiconductor layer 15. For example, thetransparent electrode layer 16 may be formed of ITO, ZnO, or Ni/Au. Thetransparent electrode layer 16 has lower specific resistance than thesecond conductivity type semiconductor layer 15 to facilitate electriccurrent distribution.

The first electrode pad 17 is disposed on a lower surface of the firstconductivity type semiconductor layer 13, and the second electrode pad18 is disposed on a lower surface of the transparent electrode layer 16.The second electrode pad 18 is electrically connected to the secondconductivity type semiconductor layer 15 through the transparentelectrode layer 16.

The reflective layer 19 covers the lower surface of the light emittingstructure 12 excluding the first electrode pad 17 and the secondelectrode pad 18. In addition, the reflective layer 19 covers the sidesurfaces of the active layer 14 and the second conductivity typesemiconductor layer 15, which are exposed by patterning to expose thefirst conductivity type semiconductor layer 13.

The reflective layer 19 reflects light generated from the active layer14 and traveling towards the second electrode pad 18 to the uppersurface or the side surface of the light emitting diode chip 110. Assuch, the reflective layer 19 causes all fractions of light generatedfrom the light emitting structure 12 to be emitted only through a lightemitting surface of the light emitting diode chip 110.

The reflective layer 19 may be an insulation layer including a singleDBR layer or multiple DBR layers, or may be a metal layer surrounded bythe insulation layer. The location and structure of the reflective layer19 are not limited that shown in FIG. 2 , and may be modified in variousways so long as the reflective layer 19 can reflect light travelingtowards the second electrode pad 18.

The light reflection member 120 is disposed on the upper surface of thelight emitting diode chip 110. The light reflection member 120 may beformed to cover the entire upper surface of the substrate 11.

Light traveling towards the upper surface of the light emitting diodechip 110 is reflected by the light reflection member 120 to be emittedthrough the side surface of the light emitting diode chip 110.

In some exemplary embodiments, ohmic contact layers for ohmic contactmay be disposed between the first conductivity type semiconductor layer13 and the first electrode pad 17, and between the second conductivitytype semiconductor layer 15 and the second electrode pad 18.

FIG. 3 is a schematic view of a light emitting device according to asecond exemplary embodiment.

Referring to FIG. 3 , a light emitting device 200 according to theillustrated exemplary embodiment includes a light emitting diode chip110, a light reflection member 120, a wavelength conversion member 230,and a light blocking member 140.

The wavelength conversion member 130 of FIG. 1 exposes the upper surfaceof the light reflection member 120, however, the wavelength conversionmember 230 according to the illustrated exemplary embodiment covers theupper surface of the light reflection member 120. More particularly, thewavelength conversion member 230 is formed to cover the side surface ofthe light emitting diode chip 110 and the upper and side surfaces of thelight reflection member 120. The light blocking member 140 covers theupper surface of the wavelength conversion member 230 and is spacedapart from the light reflection member 120 by the wavelength conversionmember 230.

As such, the light emitting device 200 according to the illustratedexemplary embodiment has a structure in which the wavelength conversionmember 230 is disposed not only on the side surface of the lightemitting diode chip 110 but also between the light reflection member 120and the light blocking member 140.

The wavelength conversion member 230 disposed between the light blockingmember 140 and the light reflection member 120 may have the samethickness as the thickness of the wavelength conversion member 230formed on the side surface of the light emitting diode chip 110, withoutbeing limited thereto. In some exemplary embodiments, the thickness ofthe wavelength conversion member 230 disposed between the light blockingmember 140 and the light reflection member 120 may be less than thethickness of the wavelength conversion member 230 formed on the sidesurface of the light emitting diode chip 110. For example, the thicknessof the wavelength conversion member 230 disposed between the lightblocking member 140 and the light reflection member 120 may be abouthalf or less the thickness of the wavelength conversion member 230formed on the side surface of the light emitting diode chip 110. Asanother example, when the wavelength conversion member 230 formed on theside surface of the light emitting diode chip 110 has a thickness of 100μm, the wavelength conversion member 230 disposed between the lightblocking member 140 and the light reflection member 120 may have athickness of 50 μm or less.

As the thickness of the wavelength conversion member 230 disposedbetween the light blocking member 140 and the light reflection member120 is decreased, light traveling towards the upper surface of the lightemitting device 200 may be more efficiently blocked. Accordingly, abacklight unit employing the light emitting device 200 according to theillustrated exemplary embodiment can achieve more uniform distributionof light emitted therefrom.

In the light emitting device 100 of FIG. 1 , the light blocking member140 contacts the light reflection member 120. Accordingly, the lightreflection member 120 is exposed until the light blocking member 140 isformed thereon, and thus, the light reflection member 120 can be damagedduring manufacture. In addition, when the light emitting device 200 issubjected to external impact, the light reflection member 120 can beseparated from the light emitting diode chip 110.

In the light emitting device 200 according to the illustrated exemplaryembodiment, the wavelength conversion member 230 covers both the lightemitting diode chip 110 and the light reflection member 120, therebypreventing the light blocking member 140 from being exposed and damaged,while preventing the light reflection member 120 from being separatedfrom the light emitting diode chip 110 by external impact.

FIG. 4 is a graph depicting brightness of a light emitting deviceaccording to an exemplary embodiment and a conventional light emittingdevice.

The graph of FIG. 4 depicts brightness depending upon a separationdistance from a center of the light emitting device.

In FIG. 4 , A is a graph depicting brightness of a light emitting deviceaccording to a comparative example and B is a graph depicting brightnessof the light emitting device according to an exemplary embodiment.

The light emitting device B according to an exemplary embodimentincludes a wavelength conversion member 230 disposed between a lightreflection member 120 and a light blocking member 140, as in the lightemitting device 200 shown in FIG. 3 . The wavelength conversion member230 disposed on an upper surface of the light reflection member 120 hasa thickness of 100 μm. Further, the wavelength conversion member 230disposed on a side surface of the light emitting diode chip 110 has athickness of 100 μm. Further, the light blocking member 140 is disposedto cover an upper surface of the wavelength conversion member 230.

The light emitting device A according to the comparative exampleincludes a light emitting diode chip 110, a light reflection member 120disposed on an upper surface of the light emitting diode chip, and awavelength conversion member 230 covering the light emitting diode chipand the light reflection member.

As such, the light emitting device A of the comparative example does notinclude the light blocking member 140 of the light emitting device Baccording to an exemplary embodiment.

The light emitting device A of the comparative example exhibits themaximum brightness and the minimum brightness repeated at constantintervals, in which there is a relatively large difference between themaximum brightness and the minimum brightness. In this case, the peak ofthe graph exhibiting the maximum brightness in each interval correspondsto an upper portion of the light emitting diode chip. As such, the lightemitting device A of the comparative example has a large difference inbrightness between the upper portion of the light emitting diode chipand a peripheral region thereof. As such, it can be seen that even withthe light reflection member 120, the light emitting device A of thecomparative example suffers from a spot phenomenon due to concentrationof light on an upper region of the light emitting diode chip, therebyexhibiting low luminous uniformity.

The light emitting device B according to an exemplary embodiment has asmaller difference between the maximum brightness and the minimumbrightness than the light emitting device A of the comparative example.As can be seen from the graph, the light emitting device B according tothe illustrated exemplary embodiment has insignificant difference inbrightness between the upper portion of the light emitting diode chipand the peripheral region thereof. Accordingly, the light emittingdevice B according to the illustrated exemplary embodiment can suppressthe spot phenomenon and improve luminous uniformity.

As such, by comparison of the light emitting device B according to theillustrated exemplary embodiment with the light emitting device A of thecomparative example, it can be seen that the light blocking membersuppresses concentration of light on the upper portion of the lightemitting diode chip. Thus, the light emitting device employing the lightblocking member has improved luminous uniformity.

FIG. 5 is a graph depicting brightness of the light emitting devicedepending upon a thickness of the wavelength conversion member betweenthe light reflection member and the light blocking member.

C1 is a graph depicting brightness of the light emitting deviceaccording to the first exemplary embodiment shown in FIG. 1 . Moreparticularly, C1 depicts brightness of the light emitting device inwhich the light reflection member 120 closely contacts the lightblocking member 140. C2 to C4 are graphs depicting brightness of thelight emitting device 200 according to the second exemplary embodiment.More particularly, the wavelength conversion member 230 between thelight reflection member 120 and the light blocking member 140 has athickness of 50 μm in C2, 100 μm in C3, and 150 μm in C4. Further, thewavelength conversion member 230 formed on the side surface of the lightemitting diode chip 110 has a thickness of 100 μm in C1 to C4.

The light emitting device has a luminous uniformity of 74% in C1, 73% inC2, 67% in C3, and 64% in C4. As such, it can be seen that luminousuniformity of the light emitting device is improved as the thickness ofthe wavelength conversion member between the light reflection member andthe light blocking member decreases.

Furthermore, for the light emitting device to have a uniform lightdistribution of 70% or more, the wavelength conversion member betweenthe light reflection member and the light blocking member has athickness of about 50 μm or less.

FIG. 6 and FIG. 7 are schematic views of light emitting devicesaccording to third and fourth exemplary embodiments.

Each of the light emitting devices 300, 400 according to the third andfourth exemplary embodiments includes a light emitting diode chip 110, alight reflection member 120, a wavelength conversion member 130; 430,and a light blocking member 340; 440.

Referring to FIG. 6 , the wavelength conversion member 130 covers a sidesurface of the light emitting diode chip 110 and a side surface of thelight reflection member 120. The light blocking member 340 covers anupper surface of the wavelength conversion member 130 while exposing anupper surface of the light reflection member 120.

Although light emitted from the light emitting diode chip 110 isreflected by the light reflection member 120, some fractions of lightmay travel upwards through the wavelength conversion member 130.Accordingly, the light blocking member 340 may be disposed in a ringshape so as to block light emitted through the upper surface of thewavelength conversion member 130.

Referring to FIG. 7 , in the fourth exemplary embodiment, the wavelengthconversion member 430 covers the side surface of the light emittingdiode chip 110 but does not cover the side surface of the lightreflection member 120. The light blocking member 440 is disposed on theupper surface of the wavelength conversion member 430 to cover the uppersurface of the wavelength conversion member 430 and the side surface ofthe light reflection member 120.

As such, in the light emitting devices 300, 400 according to the thirdand fourth exemplary embodiments, the light blocking members 340, 440are formed only on the upper surfaces of the wavelength conversionmembers 130, 430, respectively. In this manner, material costs for thewavelength conversion members 130, 430 may be reduced in the lightemitting devices 300, 400, as compared with a structure having the lightblocking member 340; 440 formed on the entire upper surfaces of thewavelength conversion member 130; 430 and the light reflection member120.

FIG. 8 is a view of a light emitting device according to a fifthexemplary embodiment.

The light emitting device 500 according to the fifth exemplaryembodiment includes a light emitting diode chip 110, a light reflectionmember 120, a wavelength conversion member 530, and a light blockingmember 540.

Referring to FIG. 8 , the wavelength conversion member 530 covers a sidesurface of the light emitting diode chip 110 and upper and side surfacesof the light reflection member 120. The upper surface of the wavelengthconversion member 530 has a stepped structure, in which a peripheralregion of the upper surface thereof has a smaller thickness than acentral region of the upper surface thereof.

The light blocking member 540 covers the upper surface of the wavelengthconversion member 530, and may fill a stepped portion of the wavelengthconversion member 530.

In this manner, a contact area between the wavelength conversion member530 and the light blocking member 540 is increased by the wavelengthconversion member 530 having the stepped structure. Increase in contactarea between the wavelength conversion member 530 and the light blockingmember 540 enhances the bonding strength therebetween. As such, thelight emitting device 500 can have improved durability through enhancedbonding strength between the wavelength conversion member 530 and thelight blocking member 540. Furthermore, since the light blocking member540 is disposed on the stepped portion formed along the edge of thewavelength conversion member 530 while covering the upper surface of thewavelength conversion member 530, light emitted through the uppersurface of the wavelength conversion member 530 may be effectivelyblocked.

FIG. 9 to FIG. 11 are schematic views illustrating a method ofmanufacturing the light emitting device according to the fifth exemplaryembodiment.

Referring to FIG. 9 , multiple light emitting diode chips 110 aremounted on a support member 610. Then, a wavelength conversion member530 is formed to cover the multiple light emitting diode chips 110.

Referring to FIG. 10 , trenches 531 are formed in regions of thewavelength conversion member 530 disposed between the multiple lightemitting diode chips 110. The trenches 531 may be formed by laser beams,exposure, cutting, and the like, depending upon the material of thewavelength conversion member 530.

Referring to FIG. 11 , a light blocking member 540 is formed on theupper surface of the wavelength conversion member 530. For example, thelight blocking member 540 may be formed by depositing a resin havinggood flowability on the upper surface of the wavelength conversionmember 530. In this manner, the trenches 531 of the wavelengthconversion member 530 are filled with the light blocking member 540.Thereafter, the light blocking member 540 may be secured after apredetermined period of time or by a separate process.

After formation of the light blocking member 540, dicing is performed toseparate adjacent light emitting diode chips 110 from each other along adicing line D shown in FIG. 11 . After the dicing process, the supportmember 610 is removed from the light emitting diode chips, therebyproviding the light emitting device 500 according to the fifth exemplaryembodiment.

FIG. 12 and FIG. 13 are schematic views of a light emitting diodepackage according to a first exemplary embodiment.

FIG. 12 is a perspective view of the light emitting diode packageaccording to the first exemplary embodiment. FIG. 13 is across-sectional view of the light emitting diode package according tothe first exemplary embodiment.

The light emitting diode package 1100 according to the first exemplaryembodiment includes a circuit board 1110, a light emitting diode chip1120, a reflection member 1130, and a dam 1140.

The circuit board 1110 supplies electric power to the light emittingdiode chip 1120. The circuit board 1110 may include an insulating resinand an interconnection pattern formed on the insulating resin. Forexample, the circuit board 1110 may be selected from any circuit boards,such as a printed circuit board (PCB), a metal PCB, a flexible printedcircuit board (FPCB), and the like.

The light emitting diode chip 1120 is disposed on the circuit board1110. The light emitting diode chip 1120 emits light upon application ofelectric power thereto through the circuit board 1110. According to anexemplary embodiment, the light emitting diode chip 1120 emits lightthrough upper and side surfaces thereof. For example, the light emittingdiode chip 1120 is a semiconductor device having a light emittingstructure on a growth substrate. The light emitting diode chip 1120 isconnected to the circuit board 1110 through flip-chip bonding, withoutbeing limited thereto.

The reflection member 1130 is formed to cover the upper surface of thelight emitting diode chip 1120. The reflection member 1130 reflectslight passing through the upper surface of the light emitting diode chip1120, such that light is emitted to the outside through the side surfaceof the light emitting diode chip 1120.

The reflection member 1130 may be formed of any material capable ofreflecting light. The reflection member 1130 may include a distributedBragg reflector (DBR). For example, the DBR forming the reflectionmember 1130 may have a monolayer structure of SiO₂, TiO₂, SiN, or TiN.Alternatively, the DBR may have a multilayer structure formed bystacking at least two layers selected from among SiO₂, TiO₂, SiN, andTiN layers. Still alternatively, the reflection member 1130 may beformed of metal, such as Ag, Al, and the like. In some exemplaryembodiments, the reflection member 1130 may include both the DBR and ametal layer.

According to the illustrated exemplary embodiment, the reflection member1130 is formed on the upper surface of the light emitting diode chip1120, thereby improving spreading of light in the lateral direction ofthe light emitting diode chip 1120. As spreading of light in the lateraldirection of the light emitting diode chip 1120 is improved, lightemitted from one light emitting diode chip 1120 can be spread over abroader region. In this manner, the light emitting diode package 1100can reduce the number of light emitting diode chips 1120.

The dam 1140 is disposed to surround a lateral side of the lightemitting diode chip 1120 on the circuit board 1110. The dam 1140 isseparated from the side surface of the light emitting diode chip 1120.In particular, the light emitting diode chip 1120 is placed in a certainregion defined by the dam 1140.

The dam 1140 may not transmit light emitted from the light emittingdiode chip 1120 therethrough. Accordingly, the dam 1140 allows at leastsome fraction of light emitted from the light emitting diode chip 1120to spread only inside a particular region. Further, the dam 1140 mayprevent at least some fraction of light emitted from another lightemitting diode chip 1120 from spreading into the particular region.

Referring to FIG. 12 and FIG. 13 , the dam 1140 is separately formed onthe circuit board 1110. More particularly, the dam 1140 may be formed asa separate component from the circuit board 1110, as shown in FIG. 13 .The dam 1140 may include a different material than the circuit board1110. For example, the dam 1140 may be formed of a silicone resin.

Alternatively, the dam 1140 may be integrally formed with the circuitboard 1110. In this case, the dam 1140 may be formed of the samematerial as the circuit board 1110.

The dam 1140 may be formed to have a height capable of maintaining beamangle characteristics of the light emitting diode package 1100 includingthe dam 1140 to be similar to beam angle characteristics of a lightemitting diode package that does not include the dam 1140.

FIG. 14 is a graph depicting beam angle depending upon an angle (θ) froman optical axis (C-axis) of the light emitting surface to an uppercorner of an inner wall of the dam 1140.

FIG. 14 shows beam angles of light emitting diode packages, in which anangle (θ) defined between the light emitting surface and the dam 1140 is65° (B), 35° (C), and the dam 1140 is not formed (D).

When the angle (θ) defined between the light emitting surface and thedam 1140 is 65° (B), the light emitting diode package has a peak beamangle (θ peak) of 48° to 54°, which is similar to the beam angle of thelight emitting diode package not including the dam 1140.

When the angle defined between the light emitting surface and the dam1140 is 35°, the light emitting diode package has a peak beam angle (θpeak) of 30° to 36°, which is different from the beam angle of the lightemitting diode package not including the dam 1140.

Accordingly, the dam 1140 is formed to have a height at which the angle(θ) from the optical axis of the light emitting surface to the uppercorner of the inner wall of the dam is greater than the peak beam angleof the light emitting diode chip 1120.

The reflection member 1130 is formed on the upper surface of the lightemitting diode chip 1120 to allow emission of light over a broad region.When the light emitting diode package includes the multiple lightemitting diode chips 1120, light emitted from adjacent light emittingdiode chip 1120 overlaps in some regions thereof. Accordingly, even whenone light emitting diode chip 1120 does not operate, some fraction oflight emitted from another light emitting diode chip 1120 adjacentthereto spreads to a region where the one light emitting diode chip 1120is disposed. In this case, clear blackout in that region where the lightemitting diode chip 1120 is disposed may not be obtained due to lightemitted from the adjacent light emitting diode chip 1120.

According to the illustrated exemplary embodiment, the dam 1140 mayrestrict a region, in which at least some fraction of light emitted fromthe light emitting diode chip 1120 can be spread. More particularly, thedam 1140 reduces an influence of light emitted from an adjacent lightemitting diode chip 1120 disposed outside the dam 1140 on a particularregion defined by the dam 1140. Accordingly, when the light emittingdiode chip 1120 disposed in the particular region defined by the dam1140 is turned off and does not emit light, clear blackout of theparticular region may be achieved.

FIG. 15 is a graph comparing beam angle of the light emitting diodepackage according to the first exemplary embodiment with beam angle of aconventional light emitting diode package.

The light emitting diode package according to the first exemplaryembodiment includes the dam formed on the circuit board and surroundingthe lateral side of the light emitting diode chip.

The conventional light emitting diode package does not include the damon the circuit board.

Both the light emitting diode package according to the first exemplaryembodiment and the typical conventional emitting diode package include areflection member formed on the upper surface of the light emittingdiode chip.

Referring to FIG. 15 , in a graph E depicting the beam angle of thelight emitting diode package according to the first exemplary embodimentand a graph F depicting the beam angle of the conventional lightemitting diode package, the peak point is exhibited at the same angle.However, it can be seen that the light emitting diode package accordingto the first exemplary embodiment has a narrower light emission zonethan the conventional light emitting diode package. As such, it can beseen that the light emitting diode package according to the firstexemplary embodiment restricts a light spreading range using the damwhile maintaining optical characteristics, such as a light peak point.

FIG. 16 is a schematic view of a light emitting diode package accordingto a second exemplary embodiment.

Referring to FIG. 16 , the light emitting diode package 1200 accordingto the second exemplary embodiment includes a circuit board 1110, alight emitting diode chip 1120, a light transmitting resin 1210, areflection member 1130, and a dam 1140.

The light transmitting resin 1210 is formed on the circuit board 1110 tosurround the light emitting diode chip 1120 and the reflection member1130. In this manner, the light transmitting resin 1210 protects thelight emitting diode chip 1120 and the reflection member 1130 frommoisture, dust, external impact, and the like. For example, the lighttransmitting resin may be a transparent epoxy resin or a transparentsilicone resin.

In some exemplary embodiments, the light transmitting resin 1210 mayinclude a wavelength conversion material dispersed therein.

The light transmitting resin 1210 with the wavelength conversionmaterial dispersed therein emits white light or a certain color lightthrough conversion of the wavelength of light emitted from the lightemitting diode chip 1120.

The wavelength conversion material may be a phosphor that converts thewavelength of light. The phosphor may include yellow phosphors, redphosphors, green phosphors, and the like.

The yellow (Y) phosphors may include, for example, silicate phosphors orYAG:Ce(T₃Al₅O₁₂:Ce) phosphors, which are cerium-doped yttrium (Y)aluminum (Al) garnets having a main wavelength of 530 nm to 570 nm.

The red (R) phosphor may include, for example, nitride phosphors or YOX(Y₂O₃:Eu) phosphors having a main wavelength of 611 nm and including acompound of yttrium oxide (Y₂O₃) and europium (Eu).

The green (G) phosphors may include, for example, LAP (LaPO₄:Ce,Tb)phosphors having a main wavelength of 544 nm and including a compound ofphosphoric acid (PO₄), lanthanum (La), and terbium (Tb).

The blue (B) phosphors may include, for example, BAM (BaMgAl₁₀O₁₇:Eu)phosphors having a main wavelength of 450 nm and including a compound ofbarium (Ba), magnesium (Mg), aluminum oxide materials, and europium(EU).

The phosphors may include fluoride compound KSF (K₂SiF₆) phosphors,which are Mn4+-activated phosphors advantageous for high colorreproduction.

As such, the wavelengths of light emitted through the side surface ofthe light emitting diode chip 1120 and light having passed through thereflection member 1130 may be converted by the light transmitting resin1210 with the wavelength conversion material dispersed therein.

In some exemplary embodiments, if wavelength conversion of light emittedfrom the light emitting diode chip 1120 is not required, the wavelengthconversion material can be omitted.

FIG. 17 to FIG. 19 are schematic views of light emitting diode packagesaccording to third to fifth exemplary embodiments.

FIG. 17 is a cross-sectional view of a light emitting diode package 1300according to the third exemplary embodiment, which includes a dam 1310having a trapezoidal cross-section.

FIG. 18 is a cross-sectional view of a light emitting diode package 1400according to the fourth exemplary embodiment, which includes a dam 1410having a semispherical cross-section.

FIG. 19 is a cross-sectional view of a light emitting diode package 1500according to the fifth exemplary embodiment, which includes a dam 1510having a curved cross-section.

The dam 1140 of the light emitting diode package 1100 according to thefirst exemplary embodiment shown in FIG. 12 and the dam 1310 of thelight emitting diode package 1300 according to the third exemplaryembodiment shown in FIG. 17 can be formed using a mold through cutting,punching, injection molding, and the like. In particular, the dam 1310of the light emitting diode package 1300 according to the thirdexemplary embodiment has an inclined side surface. The inclined sidesurface of the dam 1310 may prevent light reflected by the side surfacethereof from reentering the light emitting diode chip 1120. When the damis formed using a mold, the dams for surrounding the lateral sides ofthe plurality of light emitting diode chips 1120 may be simultaneouslyformed.

The dam 1410 of the light emitting diode package 1400 according to thefourth exemplary embodiment and the dam 1510 of the light emitting diodepackage 1500 according to the fifth exemplary embodiment may be formedusing a dispenser. The dam 1410 of the light emitting diode package 1400according to the fourth exemplary embodiment may be formed using a mold.When the dam is formed using the dispenser, it is possible to preciselyform the dam.

In this manner, the dam may be formed to have various radii of curvatureand shapes using various methods.

FIG. 20 to FIG. 23 are schematic views of light emitting diode packagesaccording to sixth to ninth exemplary embodiments.

FIG. 20 and FIG. 22 are perspective views of light emitting diodepackages 1600, 1800 according to the sixth and eighth exemplaryembodiments, and FIG. 21 and FIG. 23 are plan views of the lightemitting diode packages 1700, 1900 according to the seventh and ninthexemplary embodiments.

In the light emitting diode packages 1600, 1700, 1800, 1900 according tothe sixth to ninth exemplary embodiments, multiple light emitting diodechips 1120 are disposed on the circuit board 1110. Further, the dams1610, 1710, 1810, 1910 of the light emitting diode packages 1600, 1700,1800, 1900 according to the sixth to ninth exemplary embodiments mayhave any one of various structures shown in FIG. 20 to FIG. 23 .

In the light emitting diode packages 1600, 1700, 1800, 1900 shown inFIG. 20 to FIG. 23 , a reflection member 1130 and a light transmittingresin 1210 formed on an upper surface of each of light emitting diodechips 1120 are not separately shown. Although not shown in FIG. 20 toFIG. 23 , however, the reflection member 1130 is formed on the uppersurface of the light emitting diode chip 1120 and the light transmittingresin 1210 may also be formed, as needed.

The light emitting diode packages according to the third to ninthexemplary embodiments exemplarily illustrate that the dam may be formedto have various structures. For example, the dam 1610 and 1710 betweenadjacent light emitting diode chips 1120 may be formed on the circuitboard 1110 while being spaced apart from each other as shown in FIGS. 20and 21 . Alternatively, adjacent light emitting diode chips 1120 mayshare at least a portion of the dam 1810 and 1910 disposed therebetweenas shown in FIGS. 22 and 23 . The dam formed in the light emitting diodepackage is not limited to those shown in the illustrated exemplaryembodiments, and may be formed in various structures.

FIG. 24 is a cross-sectional view of the light emitting diode packageaccording to the sixth exemplary embodiment shown in FIG. 20 .

The light emitting diode package 1600 according to the sixth exemplaryembodiment includes multiple light emitting diode chips 1120 disposed onthe circuit board 1110 and the dams 1610 surrounding the lateral side ofeach of the light emitting diode chips 1120, as shown in FIG. 24 .

Hereinafter, a first light emitting diode chip 1120 and a second lightemitting diode chip 1120 will be described as light emitting diode chips1120 adjacent to each other.

The reflection member 1130 is formed on the upper surface of each of thefirst the light emitting diode chip 1120 and the second light emittingdiode chip 1120. Accordingly, both the first light emitting diode chip1120 and the second light emitting diode chip 1120 broadly emit light inthe lateral direction.

According to the illustrated exemplary embodiment, some fraction oflight emitted from the first light emitting diode chip 1120 is spreadthrough an upper portion of the dam 1610 to a region in which the secondlight emitting diode chip 1120 is disposed. Further, the remainingfraction of light emitted from the first light emitting diode chip 1120is blocked by the dam 1610 and does not reach the region of the secondlight emitting diode chip 1120. Some fraction of light emitted from thesecond light emitting diode chip 1120 is also spread to a region inwhich the first light emitting diode chip 1120 is disposed and theremaining fraction of the light emitted from the second light emittingdiode chip 1120 is blocked by the dam 1610.

When the second light emitting diode chip 1120 stops light emission, thedam 1610 allows only some fraction of light emitted from the first lightemitting diode chip 1120 to affect the region in which the second lightemitting diode chip 1120 is disposed. If the light emitting diodepackage does not include the dam 1610, most of light emitted from thefirst light emitting diode chip 1120 and spreading towards the secondlight emitting diode chip 1120 affects the region of the second lightemitting diode chip 1120. Accordingly, if the light emitting diodepackage is not provided with the dam 1610, the light emitted from thefirst light emitting diode chip 1120 affects the region in which thesecond light emitting diode chip 1120 is disposed, even when the secondlight emitting diode chip 1120 stops light emission.

However, the dam 1610 formed to partition the region of the first lightemitting diode chip 1120 from the region of the second light emittingdiode chip 1120 according to the illustrated exemplary embodimentreduces the influence of light emitted from the first or second lightemitting diode chip on the region in which the first or second lightemitting diode chip is disposed. Accordingly, when the second lightemitting diode chip 1120 stops light emission, the amount of lightemitted from the first light emitting diode chip 1120 and affecting theregion of the second light emitting diode chip 1120 is reduced, therebyensuring clearer blackout in the corresponding region.

The dam 1610 does not completely block light emitted from one lightemitting diode chip and affecting a region adjacent to the one lightemitting diode chip. Thus, when both the first light emitting diode chip1120 and the second light emitting diode chip 1120 are operated to emitlight, light emitted from the first light emitting diode chip 1120 andlight emitted from the second light emitting diode chip 1120 are mixedin a region therebetween, whereby the light emitting diode package 1600can emit light in a generally uniform distribution.

FIG. 25 is a graph comparing brightness of the light emitting diodepackage according to the sixth exemplary embodiment with brightness of aconventional light emitting diode package.

The light emitting diode package according to the sixth exemplaryembodiment is the light emitting diode package 1600 shown in FIG. 20 andFIG. 24 .

In the light emitting diode package according to the sixth exemplaryembodiment, the multiple light emitting diode chips are disposed on thecircuit board and the dam partitions the regions of the light emittingdiode chips from each other. In this experiment, one of the multiplelight emitting diode chips is turned off and does not emit light.

In the conventional light emitting diode package, the multiple lightemitting diode chips are disposed on the circuit board on which the damis not formed. In this experiment, one of the multiple light emittingdiode chips is turned off and does not emit light.

The position of the light emitting diode chip in a turned-off state isthe same between the light emitting diode package according to the sixthexemplary embodiment and the conventional light emitting diode package.The region of the light emitting diode chip in the turned-off state is ablackout region.

Brightness H of the light emitting diode package according to the sixthexemplary embodiment, in which the dam is formed in the blackout region,is lower than brightness I of the conventional light emitting diodepackage. Referring to FIG. 25 , the conventional light emitting diodepackage has a brightness value I of 60 or more. On the other hand, thelight emitting diode package according to the sixth exemplary embodimenthas a brightness value H of 60 or less, for example, about 50. As such,in the blackout region, the light emitting diode package according tothe sixth exemplary embodiment ensures clearer blackout than theconventional light emitting diode package.

However, in the light emitting region, the light emitting diode packageaccording to the sixth exemplary embodiment has similar brightness tothe conventional light emitting diode package.

As such, although the light emitting diode package according to theexemplary embodiments has similar brightness to that of the conventionallight emitting diode package in the light emitting regions thereof, thelight emitting diode package according to the exemplary embodiments canensure clearer blackout in the blackout region thereof by the dam ascompared to the conventional light emitting diode package. Accordingly,a display apparatus adopting the light emitting diode package includingthe dam according to the exemplary embodiments can have improvedcontrast.

FIG. 26 is a schematic view of a backlight unit according to a firstexemplary embodiment.

Referring to FIG. 26 , a backlight unit 2000 includes a light emittingdiode package 1600 and an optical member 2010.

The light emitting diode package 1600 shown in FIG. 26 may be the lightemitting diode package 1600 according to the sixth exemplary embodiment.However, the inventive concepts are not limited thereto, and in otherexemplary embodiments, the light emitting diode package 1600 may havethe structure of any one of the light emitting diode packages accordingto the other exemplary embodiments described above.

The optical member 2010 is disposed on the light emitting diode package1600. The optical member 2010 may be a light guide plate or an opticalsheet, such as a diffusion sheet, a quantum dot (QD) sheet, a diffusionsheet, a reflective film, a phosphor sheet, a prism sheet, a brightnessenhancement film (BEF), a dual brightness enhancement film (DBEF), andthe like. Alternatively, in some exemplary embodiments, both the lightguide plate and the optical sheet may be disposed on the light emittingdiode package 1600.

In a space between the light emitting diode package 1600 and the opticalmember 2010, light emitted from the multiple light emitting diode chips1120 may be mixed. The backlight unit 2000 may emit substantiallyuniform light through mixture of light emitted from the multiple lightemitting diode chips 1120.

A sealing member 2020 may be disposed in the space between the lightemitting diode package 1600 and the optical member 2010. The sealingmember 2020 may be formed of a light transmitting resin and fills thespace between the light emitting diode package 1600 and the opticalmember 2010. The sealing member 2020 may protect the light emittingdiode package 1600 from moisture, dust, external impact, and the like.

In some exemplary embodiments, the sealing member 2020 may include alight diffuser dispersed therein. The light diffuser may provide moreefficient mixture of light inside the sealing member 2020. Accordingly,the space for mixture of light can be reduced, thereby reducing thethickness of the backlight unit 2000.

FIG. 27 and FIG. 28 are schematic views of backlight units according tosecond and third exemplary embodiments.

A backlight unit 2100 according to the second exemplary embodiment and abacklight unit 2200 according to the third exemplary embodiment may beformed with dams 2110; 2210, 2220 each having a modified structure.Except for the modified dams 2110; 2210, 2220, other dams 1140 may havethe same structure as the dam 1140 according to the first or sixthexemplary embodiment described above. Hereinafter, the optical member,the reflection member, and the light transmitting resin will not beshown in the drawings for better illustration of the structure of thebacklight unit.

Referring to FIG. 27 , in the backlight unit 2100 according to thesecond exemplary embodiment, the dam 2110 is formed at each corner ofthe circuit board 1110 to be partially open towards the corner of thecircuit board 1110. A distance between the corner of the circuit board1110 and the light emitting diode chip 1120 near the corner of thecircuit board 1110 is greater than a distance between one side of thecircuit board 1110 and the light emitting diode chip 1120 near the oneside of the circuit board 1110. More particularly, the light emittingdiode chip 1120 near the corner of the circuit board 1110 emits lightover a greater region than other light emitting diode chips 1120.Accordingly, in order to allow light to spread to the corner of thecircuit board 1110, the dam 2110 has an open structure at a portionthereof facing the corner of the circuit board 1110.

Referring to FIG. 28 , the backlight unit 2200 according to the thirdexemplary embodiment includes multiple light emitting diode packages2230. In each of the light emitting diode packages 2230, the dams 2210,2220 partially surround the light emitting diode chips 1120 disposednear the corners of the circuit board 1110 and the light emitting diodechips disposed near each side of the circuit board 1110, and are opentowards the corners and sides of the circuit board 1110.

The light emitting diode chips 1120 disposed in an inner region of thecircuit board 1110 are adjacent to each other in all directions.However, the light emitting diode chips 1120 disposed along theperiphery of the circuit board 1110 do not have adjacent light emittingdiode chip 1120 towards the periphery of the circuit board 1110.Accordingly, in order to spread light towards the periphery of thecircuit board 1110, the dams 2210, 2220 are formed to be open towardsthe periphery of the circuit board 1110.

The multiple light emitting diode packages 2230 may be spaced apart fromeach other, or a reflective sheet may be disposed between the lightemitting diode packages 2230. As such, the dam 2210 is open towards aspace between the multiple light emitting diode packages 2230 to spreadlight to the space between the multiple light emitting diode packages2230. As such, the dam 2210 that may otherwise make the space betweenthe multiple light emitting diode packages 2230 darker than the lightemitting diode packages 2230 may be obviated to secure uniformbrightness of the backlight unit 2200.

FIG. 29 is a schematic partially exploded cross-sectional view of aliquid crystal display according to an exemplary embodiment, and FIG. 30is a schematic plan view of a circuit board on which light emittingdevices are arranged.

Referring to FIG. 29 and FIG. 30 , the liquid crystal display includes abacklight unit 5000 and a display panel 6000. The backlight unit 5000includes a circuit board 3011, light emitting devices 4100, a wavelengthconversion sheet 3013, a combined optical sheet 3015, and a protectivesheet 3017. The display panel 6000 may include a lower polarization film3023, a lower substrate 3021, a thin film transistor 3025, a liquidcrystal layer 3027, a transparent electrode 3035, a color filter 3033,an upper substrate 3031, and an upper polarization film 3037.

The circuit board 3011 may include a circuit pattern formed on an uppersurface or in the interior thereof. In particular, the circuit board3011 may include a circuit pattern electrically connected to each of thelight emitting devices 4100, such that the light emitting devices 4100can be independently driven.

As shown in FIG. 30 , the light emitting devices 4100 are arranged onthe circuit board 3011. The light emitting devices 4100 may be arrangedin a matrix. In particular, the light emitting devices 4100 are spacedapart from each other to implement local dimming.

Each of the light emitting devices 4100 includes a light emitting diodechip 4110 and a light reflection member 4120 formed on an upper surfaceof the light emitting diode chip 4110. In the illustrated exemplaryembodiment, the light emitting diode chip 4110 emits light through theupper and side surfaces thereof. The light emitting diode chip 4110 is asemiconductor device having a light emitting structure formed on agrowth substrate, and has a flip-chip structure having electrode padsformed on a lower surface thereof. However, the inventive concepts arenot limited to a particular structure of the light emitting diode chip4110, and in other exemplary embodiments, the light emitting diode chips4110 may have various structures, such as a horizontal type, a verticaltype, and the like.

The light reflection member 4120 reflects light emitted through theupper surface of the light emitting diode chip 4110, such that lightreflected by the light reflection member 4120 enters back to the lightemitting diode chip 4110 and is discharged through the side surface ofthe light emitting diode chip 4110. As such, the direct-lighting typebacklight unit can broadly spread light emitted from the light emittingdevices 4100 in the lateral direction, thereby increasing a luminousarea of the light emitting devices 4100.

The light reflection member 4120 may be formed of any material capableof reflecting light emitted from the light emitting diode chip 4110. Forexample, the light reflection member 4120 may be a distributed Braggreflector (DBR). The DBR may include a dielectric layer, such as SiO₂,TiO₂, SiN, and the like, and may be formed by alternately stackinglayers having different indices of refraction. Alternatively, the lightreflection member 4120 may include a metal reflector. For example, ametal reflection layer, such as Ag and Al, may be formed on the uppersurface of the light emitting diode chip 4110. Still alternatively, thelight reflection member 4120 may include both the DBR and the metalreflection layer. In particular, the DBR may have higher reflectivitythan the metal reflector to reduce light loss due to reflection oflight.

The light reflection member 4120 may be formed together with the lightemitting diode chip 4110 in a process of manufacturing the lightemitting diode chip 4110. In particular, the light reflection member4120 may be formed before individually dicing the light emitting diodechips 4110. Accordingly, the light emitting diode chip 4110 may beconsidered as including the light reflection member 120. Hereinafter,the light emitting diode chip 4110 having an upper surface through whichlight is emitted and the light reflection member 120 formed thereon willbe separately described.

The wavelength conversion sheet 3013 is disposed on the light emittingdevices 4100 and converts the wavelength of light emitted from the lightemitting devices 4100 through absorption. The wavelength conversionsheet 3013 may include a phosphor or a quantum dot.

The combined optical sheet 3015 is formed by combining at least twooptical sheets into a single sheet, and performs a combined opticalfunction. In the illustrated exemplary embodiment, the combined opticalsheet 3015 may include, for example, a prism sheet, a fine lens sheet, adiffusion sheet, and the like. Other examples of the combined opticalsheet 3015 will be described below in detail with reference to FIG. 34to FIG. 39 .

The protective sheet 3017 is disposed on the combined optical sheet 3015to protect the combined optical sheet 3015. In some exemplaryembodiments, the protective sheet 3017 may be integrated into thecombined optical sheet 3015 or may be omitted.

The display panel 6000 displays an image using light emitted from thebacklight unit 5000. The display panel 6000 includes the liquid crystallayer 3027 interposed between the lower substrate 3021 and the uppersubstrate 3031, and employs the lower polarization film 3023 and theupper polarization film 3037 to allow transmission of light or to blocklight.

The lower substrate 3021 and the upper substrate 3031 may be glasssubstrates. An active device, such as a thin film transistor, may beformed on the lower substrate 3021, and the transparent electrode 3035is formed under the upper substrate 3031 to control an alignmentdirection of liquid crystals in the liquid crystal layer 3027.

The color filter 3033 may include red, green, and blue color filters torealize a natural color image.

Although the display panel according to the illustrated exemplaryembodiment is described as having the thin film transistor 3025 formedunder the liquid crystal layer 3027 and the transparent electrode 3035formed on the liquid crystal layer 3027, the inventive concepts are notlimited thereto and the display panel may have various structures.

According to the illustrated exemplary embodiment, the backlight unitemploys the light emitting devices 4100 each including the lightreflection member 4120 formed on the upper surface of the light emittingdiode chip 4110, thereby enabling broad spreading of light. As such, adiffusion lens used in a conventional backlight unit can be obviated. Inaddition, since the backlight unit allows individual operation of thelight emitting devices 4100, the backlight unit can reduce powerconsumption while increasing contrast ratio by locally adjusting anoutput of the light emitting devices 4100 or locally turning off thelight emitting devices 4100 through local dimming.

Furthermore, the backlight unit adopts both the light emitting devices4100 and the combined optical sheet 3015 to achieve substantialreduction in thickness thereof, thereby reducing the thickness of theliquid crystal display.

Although the wavelength conversion sheet 3013 is illustrated as beingdisposed on the light emitting devices 4100 in the illustrated exemplaryembodiment, the light emitting devices 4100 may include a wavelengthconversion member and the wavelength conversion sheet 3013 may beomitted in other exemplary embodiments.

FIG. 31 is a schematic partially exploded cross-sectional view of abacklight unit of a liquid crystal display according to anotherexemplary embodiment, and FIG. 32 is a schematic enlargedcross-sectional view of a light emitting device 4200 applied to thebacklight unit shown in FIG. 31 .

Referring to FIG. 31 and FIG. 32 , although a backlight unit 5000 aaccording to the illustrated exemplary embodiment is generally similarto the backlight unit 5000 described with reference to FIG. 29 , thebacklight unit 5000 a is different from the backlight unit 5000 in thatthe backlight unit 5000 a does not include the wavelength conversionsheet 3013 and each of the light emitting devices 4200 includes awavelength conversion member 4130. More particularly, each of the lightemitting devices 4200 may include a light emitting diode chip 4110, alight reflection member 4120, and the wavelength conversion member 4130.Hereinafter, detailed descriptions of the same components alreadydescribed above will be omitted to avoid redundancy, and the followingdescriptions will focus on different features.

The wavelength conversion member 4130 may convert the wavelength oflight emitted from the light emitting diode chip 4110. The wavelengthconversion member 4130 may cover a side surface of the light emittingdiode chip 4110 and a side surface of the light reflection member 4120.

The wavelength conversion member 4130 includes a light transmittingresin 4131 and a wavelength conversion material 4132 dispersed in thelight transmitting resin 4131. For example, the light transmitting resin4131 may be formed of a light transmitting material, such as an epoxyresin, a silicone resin, and the like. For example, the wavelengthconversion material 4132 may include phosphors or quantum dots. Thephosphor refers to an inorganic or organic compound that converts lightabsorbed by the light emitting diode chip 4110 into light having adifferent wavelength depending upon difference in energy level of acompound forming the phosphor. Further, the quantum dot refers to asemiconductor nanocrystal that converts the absorbed light into lighthaving a different wavelength depending upon the magnitude of a bandgap.

As such, the wavelength of light emitted through the side surface of thelight emitting diode chip 4110 is converted by the wavelength conversionmember 4130, which covers the side surfaces of the light emitting diodechip 4110 and the light reflection member 4120. Accordingly, lightsubjected to wavelength conversion by the wavelength conversion materialis emitted through the side surface of the light emitting device 4200.Furthermore, some fraction of light emitted from the light emittingdiode chip 4110 may be emitted through the side surface of the lightemitting device 4100 without wavelength conversion.

According to the illustrated exemplary embodiment, since the lightemitting device 4200 emits light subjected to wavelength conversion, thewavelength conversion sheet 3013 (see FIG. 29 ) may be obviated from adisplay apparatus. The wavelength conversion member 4130 may not onlyconvert the wavelength of light, but also protect the light emittingdiode chip 4110 from external materials, such as moisture, dust, and thelike. In addition, the wavelength conversion member 4130 may protect thelight emitting diode chip 4110 from external impact.

Each of the light emitting devices 4200 may include the same wavelengthconversion material 4132 and may emit light having the same color, forexample, white light. However, the inventive concepts are not limitedthereto. For example, in some exemplary embodiments, the light emittingdevices 4200 may include different wavelength conversion materials fromeach other, and thus may emit light having different colors.Furthermore, a certain light emitting device 4200 may not include thewavelength conversion material 4132 depending upon a desired color oflight. For example, in the light emitting diode chip 4110 adapted toemit blue light, a separate wavelength conversion material may beobviated to emit blue light directly from the light emitting device 4200without wavelength conversion.

According to the illustrated exemplary embodiment, the wavelengthconversion sheet 3013 may be omitted, thereby enabling further reductionin thickness of the backlight unit.

FIG. 33 is a schematic cross-sectional view of a light emitting device4400 according to a further exemplary embodiment applied to a backlightunit.

Referring to FIG. 33 , although the light emitting device 4400 accordingto the illustrated exemplary embodiment is similar to the light emittingdevice 4200 described with reference to FIG. 32 , the light emittingdevice 4400 is different from the light emitting device 4200 in that awavelength conversion member 4230 of the light emitting device 4400covers a light reflection member 4120 thereof.

In the light emitting device 4200 of FIG. 32 , the wavelength conversionmember 4130 exposes the upper surface of the light reflection member4120, whereas the wavelength conversion member 4230 in the illustratedexemplary embodiment covers the upper surface of the light reflectionmember 4120. More particularly, the wavelength conversion member 4230 isformed to cover the side surface of the light emitting diode chip 4110and the upper and side surfaces of the light reflection member 4120.

The wavelength conversion member 4230 formed on the upper surface of thelight reflection member 4120 may have the same thickness as thewavelength conversion member 4230 formed on the side surface of thelight emitting diode chip 4110, without being limited thereto. Inparticular, the wavelength conversion member 4230 formed on the uppersurface of the light reflection member 4120 may have a smaller thicknessthan the wavelength conversion member 4230 formed on the side surface ofthe light emitting diode chip 4110.

In the light emitting device 4200 shown in FIG. 32 , the upper surfaceof the light reflection member 4120 is exposed, which may cause damageto the light reflection member 4120. In addition, when the lightemitting device 4200 is subjected to external impact, the lightreflection member 4120 may be separated from the light emitting diodechip 4110.

However, in the light emitting device 4400 according to the illustratedexemplary embodiment, since the wavelength conversion member 4230 coversboth the light emitting diode chip 4110 and the light reflection member4120, the light reflection member 4120 may be prevented or at least besuppressed from being damaged or being separated from the light emittingdiode chip 4110 upon application of external impact thereto.

The light emitting device applied to the backlight unit is not limitedto the light emitting devices shown in FIG. 32 and FIG. 33 . The lightemitting devices according to the exemplary embodiments described abovemay be applied to the backlight unit.

FIG. 34 to FIG. 39 are schematic cross-sectional views of a combinedoptical sheet according to exemplary embodiments.

Referring to FIG. 34 , the combined optical sheet may include a prismsheet 3015 p and a fine lens sheet 3015 m. The prism sheet 3015 p andthe fine lens sheet 3015 m may be integrated into a single combinedsheet through, for example, a bonding layer. The fine lens sheet 3015 mmay be disposed on an upper surface of the prism sheet 3015 p, or viceversa.

Referring to FIG. 35 , the combined optical sheet may include a prismsheet 3015 p and a diffusion sheet 3015 d. The prism sheet 3015 p andthe diffusion sheet 3015 d may be integrated into a single combinedsheet through, for example, a bonding layer. The diffusion sheet 3015 dmay be disposed on an upper surface of the prism sheet 3015 p, or viceversa. Alternatively, when the diffusion sheet 3015 d has a flat uppersurface and the prism sheet 3015 p is disposed thereon, the protectivesheet 3017 of FIG. 29 may be omitted.

Referring to FIG. 36 , the combined optical sheet may include a firstprism sheet 3015 p 1 and a second prism sheet 3015 p 2. The first prismsheet 3015 p 1 and the second prism sheet 3015 p 2 may be disposed tohave prism directions orthogonal to each other. The first prism sheet3015 p 1 and the second prism sheet 3015 p 2 may be integrated into asingle combined sheet through a bonding layer.

Referring to FIG. 37 , the combined optical sheet may include a prismsheet 3015 p and a polarization film 3023 a. As the polarization film3023 a is integrated into the combined optical sheet, the lowerpolarization film 3023 of FIG. 29 may be omitted together with theprotective sheet 3017.

Referring to FIG. 38 , the combined optical sheet may include twodiffusion sheets 3015 d 1, 3015 d 2 and two prism sheets 3015 p 1, 3015p 2. The diffusion sheets 3015 d 1, 3015 d 2 and the prism sheets 3015 p1, 3015 p 2 may be integrated with one another through bonding layers.As shown in the drawings, the two prism sheets 3015 p 1, 3015 p 2 may bedisposed between the two diffusion sheets 3015 d 1, 3015 d 2, withoutbeing limited thereto.

Referring to FIG. 39 , the combined optical sheet may include adiffusion sheet 3015 d, a prism sheet 3015 p, and a fine lens sheet 3015m. The diffusion sheet 3015 d, the prism sheet 3015 p, and the fine lenssheet 3015 m may be integrated into one combined sheet through bondinglayers. The combined sequence of these sheets may be changed.

Although some combined optical sheets are described above, the inventiveconcepts are not limited thereto. In some exemplary embodiments, thecombined optical sheet may include at least two sheets selected fromamong, for example, a prism sheet, a fine lens sheet, a diffusion sheet,a polarization film, and a wavelength conversion sheet, and may includethe same kind of sheet.

According to exemplary embodiments, a light emitting device may includea light reflection member and a light blocking member on a lightemitting diode chip to reflect light having passed through an uppersurface of the light emitting diode chip to be emitted through a sidesurface of the light emitting chip. Accordingly, the light emittingdevice according to the exemplary embodiments spreads light over abroader region through the side surface of the light emitting diode chipwhile suppressing light emission in an upward direction, therebysuppressing a spot phenomenon while improving luminous uniformity.

According to exemplary embodiments, each of a light emitting diodepackage and a backlight unit may include a dam formed to surround alateral side of a light emitting diode chip, thereby ensuring cleardifference in contrast ratio depending upon on/off operation of anindividual light emitting diode chip.

According to exemplary embodiments, each of the light emitting devicesmay include a distributed Bragg reflector on an upper surface thereof toemit light through a side surface of the light emitting device, therebyensuring broad distribution of light without using a separate diffusionlens. In addition, the distance between the light emitting devices canbe freely adjusted, thereby enabling arrangement of the light emittingdevices suitable for local dimming. Furthermore, the backlight unit andthe liquid crystal display may employ the light emitting devices and acombined optical sheet, thereby enabling reduction in thickness thereof.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of theappended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. A display apparatus, comprising: a display panel;and a backlight configured to provide light toward the display panel,the backlight comprising: a circuit board; an optical layer disposed onthe circuit board; at least one light emitter disposed between thecircuit board and the optical layer, the light emitter comprising: alight emitting structure disposed on the circuit board and having afirst conductivity type semiconductor layer, a second conductivity typesemiconductor layer, and an active layer disposed between the firstconductivity type semiconductor layer and the second conductivity typesemiconductor layer; a first electrode pad electrically connected to thefirst conductivity type semiconductor layer of the light emittingstructure; and a second electrode pad electrically connected to thesecond conductivity type semiconductor layer of the light emittingstructure; a reflector disposed on the light emitting structure; a lighttransmitting layer disposed on the circuit board and contacting thelight emitter; and a dam disposed on the circuit board and surroundingthe light emitter, wherein the dam has a portion having a curved shape.2. The display apparatus of claim 1, wherein the light transmittinglayer comprises a transparent epoxy resin or a transparent siliconeresin.
 3. The display apparatus of claim 2, wherein the dam surroundsthe light emitter in substantially a rectangular shape or a circularshape.
 4. The display apparatus of claim 1, wherein the dam includes aportion having a radius.
 5. The display apparatus of claim 1, whereinthe dam includes a material configured to block light emitted from thelight emitter.
 6. The display apparatus of claim 1, wherein the lighttransmitting layer includes a wavelength conversion material.
 7. Thedisplay apparatus of claim 1, wherein the optical layer comprises atleast one of a diffusion sheet, a quantum dot (QD) sheet, a reflectivefilm, a phosphor sheet, a prism sheet, a brightness enhancement film(BEF), and a dual brightness enhancement film (DBEF).
 8. The displayapparatus of claim 1, wherein the dam has a height to form an angle (θ)from an optical axis of a light emitting surface to a top surface of thedam to be greater than a peak beam angle of the light emitter.
 9. Adisplay apparatus, comprising: a circuit board; and at least one lightemitter disposed on the circuit board, the light emitter comprising: alight emitting structure disposed on the circuit board and having afirst conductivity type semiconductor layer, a second conductivity typesemiconductor layer, and an active layer disposed between the firstconductivity type semiconductor layer and the second conductivity typesemiconductor layer; a first electrode pad electrically connected to thefirst conductivity type semiconductor layer of the light emittingstructure; and a second electrode pad electrically connected to thesecond conductivity type semiconductor layer of the light emittingstructure; a light transmitting layer covering at least one surface ofthe light emitter; and a dam disposed on the circuit board andsurrounding a portion of the light emitter and a portion of the lighttransmitting layer, wherein the dam has a height to form an angle (θ)from an optical axis of a light emitting surface to a top surface of thedam to be greater than a peak beam angle of the light emitter.
 10. Thedisplay apparatus of claim 9, wherein the light transmitting layerincludes a wavelength conversion material.
 11. The display apparatus ofclaim 10, wherein the wavelength conversion material includes a phosphoror a quantum dot.
 12. The display apparatus of claim 9, wherein the damsurrounds the light emitter in substantially a rectangular shape or acircular shape.
 13. The display apparatus of claim 9, wherein the damincludes a material configured to block light emitted from the lightemitter.
 14. The display apparatus of claim 9, further comprising atransparent electrode layer comprising ITO or ZnO and disposed on thelight emitting structure.
 15. A display apparatus, comprising: a displaypanel; and a backlight configured to provide light toward the displaypanel, comprising: a circuit board; at least one light emitter disposedon the circuit board, the light emitter comprising: a substrate; a lightemitting structure disposed on the substrate and including a firstconductivity type semiconductor layer and a second conductivity typesemiconductor layer; a first electrode pad electrically connected to thefirst conductivity type semiconductor layer of the light emittingstructure; a second electrode pad electrically connected to the secondconductivity type semiconductor layer of the light emitting structure;and a reflective layer covering at least a region of the surface of thelight emitting structure; a light transmitting layer covering a surfaceof the light emitter on the circuit board; and an optical layer disposedon the light emitter and overlapping the light emitter in a thicknessdirection of the light emitter.
 16. The display apparatus of claim 15,wherein the optical layer comprises at least one of a diffusion sheet, aquantum dot (QD) sheet, a reflective film, a phosphor sheet, a prismsheet, a brightness enhancement film (BEF), and a dual brightnessenhancement film (DBEF).
 17. The display apparatus of claim 15, whereinthe light transmitting layer includes a wavelength conversion material.18. The display apparatus of claim 15, further comprising a dam disposedon the circuit board and surrounding the light emitter and the lighttransmitting layer, wherein the dam has a portion having a curved shape.19. The display apparatus of claim 18, wherein the dam has a height toform an angle (θ) from an optical axis of a light emitting surface to atop surface of the dam to be greater than a peak beam angle of the lightemitter.
 20. The display apparatus of claim 18, wherein the dam includesa portion having a radius.